Method, system, and article of manufacture for writing on sequential storage media

ABSTRACT

Provided are a method, system and article of manufacture for writing on a storage media. Data is received from a host. A determination is made whether the received data can potentially form a trailer record on the storage media. If the received data does not potentially form the trailer record, then the received data is written to the storage media.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method, system, and an articleof manufacture for writing on sequential storage media.

[0003] 2. Description of the Related Art

[0004] A host computer system may write host data onto a storage mediumlocated on a storage device. If the storage medium is a tape, then atape drive may append a trailer record at the end of the host data onthe tape. The trailer record represents the end of host data on thetape. On successive appends of host data to the tape, the tape driveoverwrites the existing trailer record and appends a new trailer recordat the end of the appended host data.

[0005] Storage media that exhibit write-once/read-many (WORM) behaviorcan be written to only once but can be read a plurality of times. Dataon WORM storage media is not subject to alteration and therefore isstored more reliably when compared to data stored in non-WORM storagemedia. WORM storage media may be useful for many applications, such as,logs and journals. Optical disks are a commonly used WORM media. Opticaldisks achieve WORM behavior because the writing process on optical disksis permanent in nature, i.e., once data is physically written on anoptical disk the data cannot be erased.

[0006] Notwithstanding the use of WORM storage media and the use oftrailer records for writing on storage media there is a need in the artfor improved techniques for writing on storage media.

SUMMARY OF THE PREFERRED EMBODIMENTS

[0007] Provided are a method, system and article of manufacture forwriting on a storage media. Data is received from a host. Adetermination is made whether the received data can potentially form atrailer record on the storage media. If the received data does notpotentially form the trailer record, then the received data is writtento the storage media.

[0008] In additional implementations, the storage media is located in astorage device, and the receiving, determining and writing are performedby the storage device. In further implementations, the received data isstored in an alternate area if the received data can potentially formthe trailer record.

[0009] In further implementations, the storage media and the alternatearea are transported and maintained within a single physical unit,wherein the alternate area is coupled to a tape cartridge, and whereinthe tape cartridge includes the storage media.

[0010] In additional implementations, the storage media is a serpentinetape, wherein the writing is on one wrap of the serpentine tape, andwherein the storing is on another wrap of the serpentine tape. Infurther implementations, the storage media is a helical ornon-serpentine tape.

[0011] In additional implementations, an alternate area exists within asame media space as the storage area, and the received data is stored inthe alternate area if the received data can potentially form the trailerrecord. In further implementations, trailer data written in thealternate area is logically invalidated by host data following thetrailer data, and the trailer data is not overwritten.

[0012] The implementations of the invention allow write-once/read-manytype of behavior on storage media.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Referring now to the drawings in which like reference numbersrepresent corresponding parts throughout:

[0014]FIG. 1 illustrates a block diagram of a computing environment, inaccordance with certain described implementations of the invention;

[0015]FIG. 2 illustrates a block diagram of a first logicalrepresentation of a tape, in accordance with certain describedimplementations of the invention;

[0016]FIG. 3 illustrates block diagrams of a second logicalrepresentation of a tape, in accordance with certain describedimplementations of the invention;

[0017]FIG. 4 illustrates logic for writing on a tape that exhibits WORMbehavior, in accordance with certain described implementations of theinvention;

[0018]FIG. 5 illustrates a block diagram of a serpentine tape thatexhibits WORM behavior, in accordance with certain describedimplementations of the invention;

[0019]FIG. 6 illustrates logic for reading from a tape that exhibitsWORM behavior, in accordance with certain described implementations ofthe invention; and

[0020]FIG. 7 illustrates a block diagram of a device architecture inwhich certain described aspects of the invention are implemented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In the following description, reference is made to theaccompanying drawings which form a part hereof and which illustrateseveral implementations. It is understood that other implementations maybe utilized and structural and operational changes may be made withoutdeparting from the scope of the present implementations.

[0022]FIG. 1 illustrates a block diagram of a computing environment, inaccordance with certain implementations of the invention. A host 100 iscoupled to a tape drive 102 via a connection 104. The host 100 may beany computational device known in the art, such as a personal computer,a workstation, a server, a mainframe, a hand held computer, a palm topcomputer, a telephony device, a network appliance, etc. The host 100 mayinclude any operating system known in the art, such as the IBM OS/390**operating system. The connection 104 may include any network known inthe art, such as the Internet, an intranet, a Local area network (LAN),a Storage area network (SAN), a Wide area network (WAN), a wirelessnetwork, etc. The network may be part of one or more larger networks ormay be an independent network or may be comprised of multipleinterconnected networks. In certain implementations, the connection 104may include any device-attach host interfaces known in the art, such asSCSI, Fibre channel, ESCON**, FICON**, etc. In alternativeimplementations, other device-attach host interfaces may be used. Thehost 100 may alternatively be connected to the tape drive 102 by theconnection 104 through direct lines, common bus systems, etc., in amanner known in the art. Various intermediate computational devices suchas a virtual tape server (not shown) may transfer data between the host100 and the tape drive 102. While only a single host 100 and a singletape drive 102 is shown, in alternative implementations a plurality ofhosts may be coupled to a plurality of tape drives. Furthermore,alternative implementations may use other storage devices known in theart that are different from the tape drive 102.

[0023] The tape drive 102 comprises a tape 106, a control logic 108, andan alternate storage area 109 coupled to the tape 106. The tape 106 maybe any type of tape known in the art, such as a serpentine tape locatedin a linear tape open (LTO) drive and includes the normal storage areafor data. The control logic 108 can perform input/output (I/O) to thetape 106, i.e., the control logic 108 can read from the tape 106 andwrite to the tape 106. The control logic 108 may be implemented insoftware, hardware, or firmware on the tape drive 102. In alternativeimplementations of the invention some or all of the functions of thecontrol logic 108 may be implemented in the host 100. In certainimplementations, the alternate storage area 109 may be physicallyseparate (i.e., a disparate mechanism) from the normal storage areaincluded in the tape 106. For example, the alternate storage area 109may be a non-volatile cartridge memory. In other implementations, thealternate storage area 109 is not physically separate from the tape 106but may be a logically or physically different storage area from thenormal storage area included within the tape 106. For example, thealternate storage area 109 may be on a different wrap or alongitudinally/laterally different portion than the normal storage areaof tape 106. The alternate storage area may also be logicallydifferentiated via formatting control or status constructs.

[0024] The control logic 108 comprises an application 110 and a trailerrecord signature database 112. The application 110 interprets commandsreceived from the host 100 and accesses entries located within thetrailer record signature database 112 prior to writing on the tape 106.The application 110 is capable of accessing the tape 106 by logicalrecords or file markers associated with the tape 106. The trailer recordsignature database 112 contains commonly used trailer records thatindicate end of data on well-known tape formats. The writing of data onthe tape 106 is such that the tape 106 exhibits a WORM behavior.

[0025]FIG. 2 illustrates a block diagram of a first logicalrepresentation of the tape 106, in accordance with certainimplementations of the invention. The application 110 interprets data onthe tape 106 to the host 100 as a sequence of logical blocks 202 a . . .202 q and file markers 204 a . . . 204 p followed by two successive filemarkers 204 q and 204 r that comprise a trailer record 206.

[0026] As a result of interpretation by the application 110, data on thetape 106 may logically appear to the host 100 as the logical blocks 202a . . . 202 q separated by the file markers 204 a . . . 204 p andfollowed by the two consecutive file markers 204 q, 204 r that comprisethe trailer record 206. The trailer record 206 indicates to the host 100that end of data has been reached on the tape 106. Such trailer records206 may be found in UNIX** type systems or in open systems. Each of thelogical blocks 202 a . . . 202 q may comprise of one or a plurality oflogical blocks, where a logical block is an arbitrary sized record ofinformation and a number of logical blocks followed by a file marker maylogically represent a file to the host 100. For example, the logicalblocks 202 a followed by the file marker 204 a may logically represent afile to the host 100. The file markers 204 a, 204 b, . . . 204 p areseparation indicators that separate successive groups of logical blocks202 a . . . 202 q.

[0027] Physically, data on the tape 106 includes the logical blocks 202a . . . 202 q and the file markers 204 a . . . 204 p. In implementationsof the invention, the tape 106 may not physically include the trailerrecord 206. The format of the trailer record 206 as represented by thetwo successive file markers 204 q, 204 r is found as an entry in thetrailer record signature database 112 and is recorded in the alternatestorage area 109.

[0028]FIG. 3 illustrates block diagrams of a second logicalrepresentation of the tape 106, in accordance with certainimplementations of the invention. The application 110 logicallyinterprets data on the tape 106 to the host 100 as a header record 300,followed by a sequence of logical blocks 302 a . . . 302 q and filemarkers 304 a . . . 304 q, followed by a trailer record 306. The headerrecord 300 and the trailer record 306 may comprise of three 80 bytelogical blocks 308, 310, 312 followed by a file marker 314. Such headerrecords 300 and trailer records 306 may be found in MVS** systems.

[0029] Physically, in the second logical representation of the tape 106,data on the tape 106 includes the header record 300, the logical blocks302 a . . . 302 q and the file markers 304 a . . . 304 q. Inimplementations of the invention, the tape 106 may not physicallyinclude the trailer record 306. The format of the trailer record 306 isfound as an entry in the trailer record signature database 112 and isrecorded in the alternate storage area 109.

[0030] The first and second logical representations of the tape 106 arerepresentative in nature and implementations of the invention may haveother logical representations of the tape 106. For example, the trailerrecords 206 and 306 may have other representations than those describedin FIGS. 2 and 3. Such alternative representations of the trailerrecords 206, 306 are also found as an entry in the trailer recordsignature database 112 and are recorded in the alternate storage area109.

[0031]FIG. 4 illustrates logic for writing on the tape 106 that exhibitsWORM behavior, in accordance with certain implementations of theinvention. The logic of FIG. 4 is implemented by the application 110located in the tape drive 102.

[0032] Control starts at block 400 where the application 110 receives awrite request and corresponding data from the host 100. The dataaccompanying the write request from the host 100 may be a part of alogical block (such as part of logical blocks 202 a or 302 a), a filemarker (such as file marker 204 a, 304 a), part of a header record (suchas part of header record 300), or part of a trailer record (such as partof trailer record 206, 306). It should be noted that the header recordsdo not need to be specially recorded except as candidates for trailerrecords in the database 112, if the header records resemble thestructure of a known trailer record. The header records are notoverwritable in a WORM environment.

[0033] Control proceeds to block 402, where the application 110determines if the received host data potentially lead to the formationof a trailer record in combination with any data previously received orany data that can be potentially received in the future. For example, ifthe application 110 receives the 80 byte record 310 immediately afterreceiving the 80 byte record 308 then the received 80 byte record 310may lead to the formation of a trailer record. In the case of opensystems where two consecutive file markers form a trailer record, whenthe application 110 receives a file marker, the file marker maypotentially lead to the trailer record 206. To determine if the receivedhost data may potentially lead to the formation of a trailer record, theapplication 110 may access the database 112 where the signature of allpotential trailer records are stored. Various schemes known in art suchas substring matching, etc., may be used to determine if a string ofsuccessively received data may potentially be the beginning part of atrailer record.

[0034] If at block 402 the application 110 determines that the receiveddata can potentially lead to the formation of a trailer record controlproceeds to block 404. At block 404 the application 110 writes thereceived data in a corresponding part of the alternate storage area 109that is different from the area of the tape 106 where host data isstored. For the tape 106 to exhibit WORM behavior, areas of the tape 106where host data is written can never be overwritten with other data.Therefore, trailer records are never written to the areas of the tape106 where host data is written. The alternate storage area 109 may be inanother wrap of the tape 106 or may be in other persistent storage thatis coupled to the physical housing that comprises the tape cartridgecorresponding to the tape 106. To elaborate, tape 106 represents a dataarea that is distinct from the alternate storage area 109, even thoughin certain implementations the alternate storage area 109 may physicallybe located on the recording media comprising the tape 106. Controlreturns to block 400, where the application 110 receives further datafrom the host 100.

[0035] If at block 402 the application 110 determines that the receivedhost data cannot potentially lead to the formation of a trailer recordcontrol proceeds to block 406. At block 406 the application 110determines if the corresponding part of the alternate storage area 109is empty. If the corresponding part of the alternate storage area isempty, then the received data is not a trailer record and controlproceeds to block 410 where the application 110 writes the received datato the area of the tape 106 where host data is stored. After writing thereceived data the alternate area 109 is cleared. Control returns toblock 400.

[0036] If at block 406 the application 110 determines that thecorresponding part of the alternate storage area 109 is not empty, thenthe data already written in the corresponding part of the alternatestorage area 109 when appended with the received data is not a trailerrecord. Therefore, at block 408 the data already written in thecorresponding part of the alternate storage area 109 is copied to thetape 106. Control proceeds to block 410 where the received data iswritten to the tape 106. Control returns to block 400.

[0037] The logic described in FIG. 4 stores host data without thetrailer record in a specific area of the tape 106 where no overwritingis allowed. The trailer record is stored in an alternate storage area109 coupled to the tape.

[0038]FIG. 5 illustrates a block diagram of a logical representation ofthe tape 106, where the tape 106 is logically represented as aserpentine tape 500 that exhibits WORM behavior, in accordance withcertain implementations of the invention. The logic of FIG. 4 may causethe serpentine tape 500 to exhibit WORM behavior.

[0039] In the serpentine tape 500 there are a plurality of wraps (wraps0 . . . n that are represented by reference numerals 502, 504, 506, 508)where information may be written in a manner known in the art. Incertain implementations, the application 110 may write host data withoutthe trailer record 510 to the oth wrap 502 and the trailer record 512 tothe (n−1)^(th) wrap 506. Data on the 0^(th) wrap 502 is neveroverwritten, whereas data on the (n−1)^(th) wrap 506 may be overwritten.

[0040] The serpentine tape 500 thus uses the (n−1)^(th) wrap 506 as thealternate storage area 109 for the 0^(th) wrap 502 of the serpentinetape 500 to exhibit WORM behavior. In alternative implementations othertape formats may be used. Similarly instead of using another wrap of thetape 106 as the alternate storage area 109, the alternate storage area109 may be any persistent storage that is not part of the tape 106.

[0041]FIG. 6 illustrates logic for reading from the tape 106 thatexhibits WORM behavior, in accordance with certain implementations ofthe invention. The logic of FIG. 6 is performed by the application 110.

[0042] Control starts at block 600 where the application 110 waits for alocate or read request from the host 100 and establishes the desiredrecord corresponding the locate or read request if needed. Theinformation returned by the application 110 to the host 100 in responseto the locate or read request should be identical to what the host 100would receive if the trailer records were not part of the alternatestorage area 109. Note that header records can be recorded normally andno special determination is required at read time for the headerrecords.

[0043] Control proceeds to block 604 where the application 110determines if the current record corresponding to the read or locaterequest exist on the normal storage area of the tape 106. If so, controlproceeds to block 606 where the application 110 processes records fromthe normal storage area of the tape 106, updates the record position,and then returns control back to block 600. Processing the records atblock 604 may include returning information to the host 100 in responseto the read or locate requests.

[0044] If at block 604, the application 110 determines that the currentrecord does not exist in the normal storage area of the tape 106 controlproceeds to block 606. At block 606, the application 110 determines ifthere is any unsent record in the alternate storage area 109. If so, theapplication 110 sends (at block 608) the unsent records from alternatestorage area 109 to the host 100 and updates the record position.Subsequently, the application 110 returns control to block 600.

[0045] If at block 606, the application 110 determines that there is nounsent record in the alternate storage area 109 control proceeds toblock 610. At block 610, the application 110 reports to the host 100that end of media has been encountered and returns control to block 600.

[0046] The logic of FIG. 6 allows the tape 106 to exhibit WORM behaviorby having the application 110 interpret the data on the tape 106 and thealternate area 109 in a manner such that it is not apparent to the host100 that the trailer records were stored in the alternate area 109.

[0047] In the described implementations, the WORM behavior is achievedby having an alternate storage area 109 in a different media space fromthe normal storage area of the tape 106. Implementations may be adaptedfor cases where the drive recording format, i.e. the low level logicalformat, is write-skipping. This allows the alternate storage area 109 toexist within the same media space as the unwritable data (i.e. thenormal storage area of the tape 106) but to be logically invalidated bydata which follows data written in the alternate storage area 109. Inthis case, the data including the trailers, is truly never overwritten,but a device format construct causes the older copies to be ignored aspart of the read process.

[0048] Storage media that exhibit write once read many (WORM) behaviormay not have data overwritten on the storage media. Although opticaldrives may be used for achieving WORM behavior, such optical drives arevery slow when compared to tape drives. Implementations of the inventionachieve WORM behavior on storage tapes and analogous storage media. Thetrailer records are not written in the same area as the host data, andtherefore the area where host data is written never needs to beoverwritten. However, from the perspective of the host the tape stillappears to comprise of logical blocks separated by file markers andending with a trailer record. The implementations of the inventionreduce the risk of data loss in storage media. Furthermore, theapplication that implements WORM behavior is located in the tape driveitself.

Additional Implementation Details

[0049] The described techniques may be implemented as a method,apparatus or article of manufacture using standard programming and/orengineering techniques to produce software, firmware, hardware, or anycombination thereof. The term “article of manufacture” as used hereinrefers to code or logic implemented in hardware logic (e.g., anintegrated circuit chip, Programmable Gate Array (PGA), ApplicationSpecific Integrated Circuit (ASIC), etc.) or a computer readable medium(e.g., magnetic storage medium, such as hard disk drives, floppy disks,tape), optical storage (e.g., CD-ROMs, optical disks, etc.), volatileand non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs,DRAMs, SRAMs, firmware, programmable logic, etc.). Code in the computerreadable medium is accessed and executed by a processor. The code inwhich implementations are made may further be accessible through atransmission media or from a file server over a network. In such cases,the article of manufacture in which the code is implemented may comprisea transmission media, such as a network transmission line, wirelesstransmission media, signals propagating through space, radio waves,infrared signals, etc. Of course, those skilled in the art willrecognize that many modifications may be made to this configurationwithout departing from the scope of the implementations, and that thearticle of manufacture may comprise any information bearing medium knownin the art.

[0050]FIG. 7 illustrates a block diagram of a device architecture inwhich certain aspects of the invention are implemented. FIG. 7illustrates elements associated with one implementation of the host 100and the tape drive 102. The host 100 and the tape drive 102 mayimplement a device architecture 700 having a processor 702, a memory 704(e.g., a volatile memory device), and a storage 706 (e.g., non-volatilestorage, magnetic disk drives, optical disk drives, tape drives, etc.).The storage 706 may comprise an internal storage device, an attachedstorage device or a network accessible storage device. Programs in thestorage 706 may be loaded into the memory 704 and executed by theprocessor 702 in a manner known in the art. The architecture may furtherinclude a network card 708 to enable communication with a network. Thearchitecture may also include at least one input 710, such as akeyboard, a touchscreen, a pen, voice-activated input, etc., and atleast one output 712, such as a display device, a speaker, a printer,etc.

[0051] The logic of FIGS. 4 and 6 describe specific operations occurringin a particular order. Further, the operations may be performed inparallel as well as sequentially. In alternative implementations,certain of the logic operations may be performed in a different order,modified or removed and still implement implementations of the presentinvention. Morever, steps may be added to the above described logic andstill conform to the implementations. Yet further steps may be performedby a single process or distributed processes.

[0052] In alternative implementations, the application 110 may be in thehost 100 rather than in the tape drive 102. Also, while the host 100 andthe tape drive 102 communicate within a client-server paradigm in thedescribed implementations, the hosts 102 and the tape drive 102 may alsocommunicate within a peer-to-peer or any other paradigm known in theart. Furthermore, many of the software and hardware components have beendescribed in separate modules for purposes of illustration. Suchcomponents may be integrated into a fewer number of components ordivided into a larger number of components. Additionally, certainoperations described as performed by a specific component may beperformed by other components.

[0053] The data structures shown in FIGS. 2 and 3 show the datastructures as having specific types of information. In alternativeimplementations, the data structures may have fewer, more or differentfields than shown in the figures.

[0054] Certain groups of elements shown in the figures have been labeledwith reference numerals having an identical numeric prefix followed bythe suffix “a”, the suffix “b”, or the suffix “n”. For example, logicalblocks are labeled 204 a . . . 204 q and 304 a . . . 304 q. Labelinggroups of elements in such a manner does not imply that different groupsof elements contain an identical number of elements in each group. Forexample, the number of logical blocks 204 a . . . 204 q need not be thesame as the number of logical blocks 304 a . . . 304 q.

[0055] Therefore, the foregoing description of the implementations hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many implementations of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A method for writing on a storage media,comprising: receiving data from a host; determining if the received datacan potentially form a trailer record on the storage media; and writingthe received data to the storage media if the received data does notpotentially form the trailer record.
 2. The method of claim 1, whereinthe storage media is located in a storage device, and wherein thereceiving, determining and writing are performed by the storage device.3. The method of claim 1, further comprising: storing the received datain an alternate area if the received data can potentially form thetrailer record.
 4. The method of claim 3, wherein the storage media andthe alternate area are transported and maintained within a singlephysical unit, wherein the alternate area is coupled to a tapecartridge, and wherein the tape cartridge includes the storage media. 5.The method of claim 3, wherein the alternate area is a persistentstorage coupled to a the storage media.
 6. The method of claim 3,wherein the storage media is a serpentine tape, wherein the writing ison one wrap of the serpentine tape, and wherein the storing is onanother wrap of the serpentine tape.
 7. The method of claim 3, whereinthe storage media is a helical or non-serpentine tape.
 8. The method ofclaim 3, further comprising: receiving a read request from the host;sending data records from the storage media to the host; and sending thetrailer record from the alternate area to the host.
 9. The method ofclaim 1, wherein the written data on the storage media is notoverwritten by any additional data received from the host.
 10. Themethod of claim 1, wherein the trailer record comprises of twosuccessive file markers or comprises of a plurality of predeterminedrecords followed by a file marker.
 11. The method of claim 1, wherein acontrol logic is coupled to a database comprising a plurality of knowntrailer records, and wherein the control logic determines if thereceived data can potentially form a trailer record on the storage mediaby comparing the received data with the plurality of known trailerrecords.
 12. The method of claim 1, wherein an alternate area existswithin a same media space as the storage area, further comprising:storing the received data in the alternate area if the received data canpotentially form the trailer record.
 13. The method of claim 12, whereintrailer data written in the alternate area is logically invalidated byhost data following the trailer data, and wherein the trailer data isnot overwritten.
 14. A system for writing on a storage media,comprising: a host; a storage media coupled to the host; means forreceiving data from the host; means for determining if the received datacan potentially form a trailer record on the storage media; and meansfor writing the received data to the storage media if the received datadoes not potentially form the trailer record.
 15. The system of claim14, wherein the storage media is located in a storage device, andwherein the receiving, determining and writing are performed by thestorage device.
 16. The system of claim 14, further comprising: meansfor storing the received data in an alternate area if the received datacan potentially form the trailer record.
 17. The system of claim 16,wherein the storage media and the alternate area are transported andmaintained within a single physical unit, wherein the alternate area iscoupled to a tape cartridge, and wherein the tape cartridge includes thestorage media.
 18. The system of claim 16, wherein the alternate area isa persistent storage coupled to a the storage media.
 19. The system ofclaim 16, wherein the storage media is a serpentine tape, wherein thewriting is on one wrap of the serpentine tape, and wherein the storingis on another wrap of the serpentine tape.
 20. The system of claim 16,wherein the storage media is a helical or non-serpentine tape.
 21. Thesystem of claim 16, further comprising: means for receiving a readrequest from the host; means for sending data records from the storagemedia to the host; and means for sending the trailer record from thealternate area to the host.
 22. The system of claim 14, wherein thewritten data on the storage media is not overwritten by any additionaldata received from the host.
 23. The system of claim 14, wherein thetrailer record comprises of two successive file markers or comprises ofa plurality of predetermined records followed by a file marker.
 24. Thesystem of claim 14, wherein a control logic is coupled to a databasecomprising a plurality of known trailer records, and wherein the controllogic determines if the received data can potentially form a trailerrecord on the storage media by comparing the received data with theplurality of known trailer records.
 25. The system of claim 14, whereinan alternate area exists within a same media space as the storage area,further comprising: means for storing the received data in the alternatearea if the received data can potentially form the trailer record. 26.The system of claim 25, wherein trailer data written in the alternatearea is logically invalidated by host data following the trailer data,and wherein the trailer data is not overwritten.
 27. An article ofmanufacture for writing on a storage media, wherein the article ofmanufacture is capable of causing operations, the operations comprising:receiving data from a host; determining if the received data canpotentially form a trailer record on the storage media; and writing thereceived data to the storage media if the received data does notpotentially form the trailer record.
 28. The article of manufacture ofclaim 27, wherein the storage media is located in a storage device, andwherein the receiving, determining and writing are performed by thestorage device.
 29. The article of manufacture of claim 27, theoperations further comprising: storing the received data in an alternatearea if the received data can potentially form the trailer record. 30.The article of manufacture of claim 29, wherein the storage media andthe alternate area are transported and maintained within a singlephysical unit, wherein the alternate area is coupled to a tapecartridge, and wherein the tape cartridge includes the storage media.31. The article of manufacture of claim 29, wherein the alternate areais a persistent storage coupled to a the storage media.
 32. The articleof manufacture of claim 29, wherein the storage media is a serpentinetape, wherein the writing is on one wrap of the serpentine tape, andwherein the storing is on another wrap of the serpentine tape.
 33. Thearticle of manufacture of claim 29, wherein the storage media is ahelical or non-serpentine tape.
 34. The article of manufacture of claim29, the operations further comprising: receiving a read request from thehost; sending data records from the storage media to the host; andsending the trailer record from the alternate area to the host.
 35. Thearticle of manufacture of claim 27, wherein the written data on thestorage media is not overwritten by any additional data received fromthe host.
 36. The article of manufacture of claim 27, wherein thetrailer record comprises of two successive file markers or comprises ofa plurality of predetermined records followed by a file marker.
 37. Thearticle of manufacture of claim 27, wherein a control logic is coupledto a database comprising a plurality of known trailer records, andwherein the control logic determines if the received data canpotentially form a trailer record on the storage media by comparing thereceived data with the plurality of known trailer records.
 38. Thearticle of manufacture of claim 27, wherein an alternate area existswithin a same media space as the storage area, the operations furthercomprising: storing the received data in the alternate area if thereceived data can potentially form the trailer record.
 39. The articleof manufacture of claim 38, wherein trailer data written in thealternate area is logically invalidated by host data following thetrailer data, and wherein the trailer data is not overwritten.